JP2005201083A - Injection control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection control device for an internal combustion engine capable of suitably suppressing accumulation of deposit at the nozzle hole of an injection valve for a cylinder, in an internal combustion engine having the injection valve for a cylinder to inject fuel in the cylinder in addition to an injection valve for an intake passage to inject fuel in the intake passage. <P>SOLUTION: An ECU 31 forcibly switches from an injection valve 22 for a port to the injection valve 21 for a cylinder such that fuel is injected by the injection valve 21 for a cylinder into each of cylinders #1-#4 for a given period for each cylinder in case it is detected that an actual fuel injection amount of the injection valve 21 for a cylinder is less than a target injection amount. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an injection control device for an internal combustion engine, and more specifically, an in-cylinder fuel injection valve that directly injects fuel into a cylinder and a fuel injection valve for an intake passage that injects fuel into an intake passage. The present invention relates to an injection control device for an internal combustion engine.

  2. Description of the Related Art Conventionally, one type of internal combustion engine of this type includes an in-cylinder injection valve that directly injects fuel into a cylinder in addition to a port injection valve that injects fuel into an intake port of an intake passage. (For example, refer to Patent Document 1). In such an internal combustion engine, the fuel injection mode can be flexibly changed according to the engine operating state, such as fuel injection using only a port injection valve, fuel injection using only an in-cylinder injection valve, or fuel injection using both of them. To switch to.

  Incidentally, since the in-cylinder injection valve is exposed to high-temperature combustion gas in the combustion chamber, deposits easily adhere to the injection hole portion of the injection valve. Further, during the operation in which the fuel injection is performed by the port injection valve as described above, the fuel injection from the in-cylinder injection valve is not performed. As a result, the deposit is further deposited on the nozzle hole portion. Such deposits hinder fuel injection from the nozzle hole, change the shape of the fuel spray (increase the particle size), or reduce the fuel injection amount below the required amount, thereby causing misfires and eventually worsening combustion. There was a risk of inviting.

Therefore, for example, in the above-mentioned Patent Document 1, even in the operation region where the port injection valve is used, a part of the fuel injection amount of the port injection valve is shared by the in-cylinder injection valve. There has been proposed a method for suppressing the accumulation of deposits by cooling due to vaporization.
JP 2002-364409 A

  However, in the method in which a part of the fuel injection amount of the port injection valve is shared by the in-cylinder injection valve as described above, when the required fuel injection amount is small, the in-cylinder that shares a part of the injection amount. Since the injection quantity of the injection valve is also reduced, there is a problem that a sufficient cooling effect cannot be obtained, and therefore deposits cannot be suitably suppressed.

  In particular, the required fuel injection amount is small so that the injection amount shared by the in-cylinder injection valve is less than the minimum injection amount of the injection valve (the minimum value that can ensure the linearity of the injection amount with respect to the valve opening time). In such a case, the in-cylinder injection valve could not perform normal fuel injection, and there was a risk of causing misfire and consequently deterioration of combustion.

  The present invention has been made in view of such conventional circumstances, and an object thereof is to provide an in-cylinder injection valve for injecting fuel into a cylinder in addition to an intake passage injection valve for injecting fuel into the intake passage. An object of the present invention is to provide an injection control device for an internal combustion engine that can suitably suppress deposit accumulation in an injection hole of an in-cylinder injection valve.

  In order to achieve the above object, according to the first aspect of the present invention, an in-cylinder injection valve that injects fuel into a cylinder of an internal combustion engine, an intake passage injection valve that injects fuel into an intake passage, and each of these injections An internal combustion engine injection control apparatus comprising: a switching unit configured to switch a fuel injection mode by drivingly controlling at least one of the valves; and the switching unit includes the cylinder in an operation region in which fuel injection is performed by the intake passage injection valve. The gist is to execute control for forcibly switching the fuel injection mode so that fuel injection by only the internal injection valve is performed for a predetermined period.

  According to the above configuration, even in the operation region where the fuel injection by the intake passage injection valve is performed, the fuel injection by the in-cylinder injection valve alone is performed for a predetermined period, so that the injection of the in-cylinder injection valve is performed. Deposits deposited in the holes can be blown off by the jetting force to remove the deposits. Further, by performing fuel injection by such an in-cylinder injection valve, it is possible to cool the nozzle hole part due to the vaporization of the fuel, and to prevent deposits from newly accumulating in the nozzle hole part. As a result, it can suppress that the fuel injection quantity of the cylinder injection valve falls.

  By the way, in the forced switching control according to the present invention, the injection valve to be used is completely switched to the in-cylinder injection valve for a predetermined period. Since it is avoided that the fuel injection amount supplied from the injection valve to the combustion chamber decreases and falls below the minimum injection amount of the in-cylinder injection valve, combustion deterioration does not occur.

  Here, in the forcible switching control, it is desirable to provide an upper limit value for the “predetermined period” in which fuel injection is performed only by the in-cylinder injection valve. That is, if the period for performing forced switching is indefinite, there is a concern about the problem of deterioration of combustion due to continuous fuel injection by the in-cylinder injection valve, but this is limited to a predetermined period (for example, a predetermined cycle). By adopting the forced switching control, it is possible to remove and suppress deposits without causing deterioration of combustion.

  The “operating region in which fuel injection is performed by the intake passage injection valve” refers to an operating region in which fuel injection is performed only by the intake passage injection valve, as well as in-cylinder in addition to the intake passage injection valve. An operation region in which fuel injection by the injection valve is performed is also included.

  According to a second aspect of the present invention, in the injection control device according to the first aspect, the switching means detects that the temperature of the injection hole of the in-cylinder injection valve or the temperature of the fuel is equal to or lower than a predetermined temperature. The gist is to execute the control for forcibly switching the fuel injection mode on the condition that

  It is the present application that the effect of blowing deposits deposited in the injection hole portion of the in-cylinder injection valve by the injection force is increased as the temperature of the injection hole portion of the in-cylinder injection valve or the temperature of the fuel is lower than a predetermined temperature. It has also been confirmed by the inventor. For this reason, it is possible to further enhance the deposit removal and suppression effect by executing the control for forcibly switching the fuel injection mode under such conditions.

  According to a third aspect of the present invention, in the injection control device according to the first or second aspect, the switching means forces the fuel injection mode until the internal combustion engine stops after the ignition switch is turned off. The gist is to execute control to switch automatically.

  According to the above configuration, the control for forcibly switching the fuel injection mode is performed after the ignition switch is turned off, that is, when the engine is stopped. Therefore, it is possible to suitably take measures against deposits while avoiding the influence of deterioration of combustion caused by fuel injection by the in-cylinder injection valve as much as possible.

  According to a fourth aspect of the present invention, in the injection control device according to any one of the first to third aspects, the detecting means detects that the actual fuel injection amount of the in-cylinder injection valve is less than the target injection amount. The switching means forcibly switches the fuel injection mode on the condition that the detection means detects that the actual fuel injection amount is less than the target injection amount. The gist is to do.

  According to the above configuration, it is detected that the actual fuel injection amount of the in-cylinder injection valve is less than the target injection amount, and based on this, deposit accumulation in the injection hole portion of the in-cylinder injection valve is monitored. I am doing so. When the actual fuel injection amount is less than the target injection amount, it is determined that the deposit is accumulated, and control for forcibly switching the previous fuel injection mode is executed. That is, according to the configuration, the switching control is performed when deposits are accumulated in the injection hole portion of the in-cylinder injection valve, and it is possible to avoid unnecessary control as much as possible. become able to.

  In particular, when this configuration is applied to the configuration described in claim 3, since the control for switching the fuel injection mode is performed only when deposits are accumulated, the fuel injection is originally performed. This makes it possible to avoid unnecessary fuel injection when the engine is not required to be stopped.

  According to a fifth aspect of the present invention, in the injection control device according to any one of the first to fourth aspects, the amount of deposit deposited in the injection hole portion of the in-cylinder injection valve is based on the engine operating state. Estimating means for estimating is further provided, and the switching means executes control for forcibly switching the fuel injection mode on condition that the deposit accumulation amount estimated by the estimating means exceeds an allowable value. This is the gist.

  According to the said structure, an estimation means estimates the deposit amount of the deposit accumulated in the nozzle hole part of the injection valve for cylinders. At this time, if the deposit accumulation amount estimated by the estimation means exceeds the allowable value, the fuel injection amount of the in-cylinder injection valve may be reduced. Therefore, deposits can be removed and suppressed by executing control for forcibly switching the fuel injection mode under such conditions.

In order to estimate the deposit amount deposited in the injection hole portion of the in-cylinder injection valve based on the engine operating state in this way, for example,
According to a sixth aspect of the present invention, the estimation means integrates the deposit amount per time estimated based on the engine operating state, and uses the accumulated value as the deposit amount. Can be adopted.

  Incidentally, in this case, as the engine operating state, parameters having a correlation with the temperature of the nozzle hole and the engine combustion state, for example, parameters such as the engine rotation speed, the engine cooling water temperature, the engine load, and the like can be used. In this estimation, in addition to a method of estimating these parameters individually, a method of estimating these parameters in combination, a method of weighting these parameters according to the degree of correlation with deposit accumulation, etc. Can be adopted.

  The gist of the invention according to claim 7 is that, in the injection control device according to claim 1, the switching means periodically executes control for forcibly switching the fuel injection mode with a predetermined period.

  According to the above configuration, it is possible to suitably take measures against deposits while avoiding as much as possible the influence of deterioration of combustion caused by always using the in-cylinder injection valve. Incidentally, as a specific mode at the time of “execution periodically with a predetermined period”, a mode of switching once every several minutes, a mode of switching once every several cycles, or the like can be adopted.

  According to an eighth aspect of the present invention, in the injection control device according to any one of the first to seventh aspects, the in-cylinder injection valve is provided corresponding to each cylinder of the internal combustion engine, The gist of the switching means is that the control for forcibly switching the fuel injection mode is sequentially executed while being limited to a part of the cylinders.

  According to the above configuration, it is possible to suitably take measures against deposits while avoiding as much as possible the influence of deterioration of combustion caused by always using the in-cylinder injection valve. In other words, according to this configuration, the in-cylinder injection valve corresponding to each cylinder can be sequentially switched by a part of the injection valves, so that the exercise performance originally intended by using the intake passage injection valve can be improved. The deposit can be suitably removed and suppressed without being lowered by switching to the internal injection valve.

(First embodiment)
A first embodiment of an internal combustion engine injection control apparatus according to the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic configuration diagram showing an injection control device of the present embodiment.
The injection control device includes a fuel supply system 20 that supplies fuel to the internal combustion engine 10, a control system 30 that controls fuel injection by the fuel supply system 20, and the control system 30 as a part of control data. And a detection system 40 including various sensors that output signals.

  The fuel supply system 20 of the injection control device is provided corresponding to each cylinder # 1 to # 4 (for example, four cylinders in the present embodiment) of the internal combustion engine 10, and the combustion chamber 11 of each cylinder # 1 to # 4. An in-cylinder injection valve 21 that directly injects fuel into the cylinder and an intake passage injection valve 22 that is provided corresponding to each cylinder # 1 to # 4 and injects fuel into the intake passage 12 are provided. In the present embodiment, the intake passage injection valve 22 is configured as a port injection valve that injects fuel into the intake port 12a that forms part of the intake passage 12, but the present invention is not limited to this configuration. It may be one that injects fuel into a surge tank 12b that constitutes a part of the intake passage 12 (generally called a cold start injector). Hereinafter, the intake passage injection valve 22 is referred to as a “port injection valve 22”.

  The fuel stored in the fuel tank 23 is distributed and supplied to the cylinder injection valve 21 and the port injection valve 22. That is, the fuel in the fuel tank 23 is pumped up by the feed pump 24 and supplied to the port injection valve 22. A part of the fuel pumped up by the feed pump 24 is pressurized to a high pressure by the supply pump 25 and then supplied to the in-cylinder injection valve 21 through the delivery pipe 26.

  Each of the in-cylinder injection valve 21 and the port injection valve 22 includes an electromagnetic solenoid (not shown) therein, and these are based on a drive signal from the control system 30 input to the electromagnetic solenoid. The fuel injection amount and fuel injection timing of each injection valve 21 and 22 are set.

  The internal combustion engine 10 is provided with spark plugs 13 corresponding to the respective cylinders # 1 to # 4. Each ignition plug 13 is connected to an igniter 14 having a built-in ignition coil (not shown). The ignition timing is set based on an ignition signal output from the control system 30 to the igniter 14.

  A throttle valve 15 that adjusts the amount of intake air introduced into the combustion chamber 11 through the intake passage 12 is provided upstream of the surge tank 12 b in the intake passage 12. The opening degree of the throttle valve 15 is adjusted by the throttle motor 16 controlled by the control system 30.

  The control system 30 of the injection control device includes an electronic control device (hereinafter referred to as “ECU”) 31 that controls various operations of the internal combustion engine 10, and an in-cylinder injection valve 21 and a port injection valve that are driven and controlled through the ECU 31. 22 electromagnetic solenoids, an igniter 14 and a throttle motor 16 are provided.

  The ECU 31 outputs a drive signal to a calculation unit 32 that executes calculation processing, a storage unit 33 that stores various control programs and data referred to when the control program is executed, and the injection valves 21 and 22 (electromagnetic solenoids). The unit 34, the input unit 35 to which detection signals of various sensors are input, and the like.

  A starter 17 that drives a crankshaft (not shown) of the internal combustion engine 10 is connected to the output unit 34 until the internal combustion engine 10 can be independently operated when the engine is started. The start operation (cranking) by the starter 17 is started when an ignition switch (not shown) is switched to the start position.

The detection system 40 of the injection control device includes an accelerator sensor 41, a water temperature sensor 42, a throttle sensor 43, a rotation speed sensor 44, a cylinder discrimination sensor 45, and the like.
The accelerator sensor 41 is provided in the vicinity of the accelerator pedal 18 and detects the amount of depression (accelerator opening). The water temperature sensor 42 is provided in a water jacket (not shown) of the internal combustion engine 10 and detects the temperature of the engine cooling water (engine cooling water temperature). The throttle sensor 43 detects the opening of the throttle valve 15 (throttle opening). Any of the detection signals of these sensors 41 to 43 is appropriately A / D (analog / digital) converted by the input unit 35 and then taken into the calculation unit 32.

  The rotation speed sensor 44 is provided in the vicinity of a crankshaft (not shown) and outputs a detection signal corresponding to the rotation. The cylinder discrimination sensor 45 is provided in the vicinity of a camshaft (not shown) and outputs a detection signal corresponding to its rotation. Both of the detection signals of these sensors 44 and 45 are waveform-shaped at the input unit 35 and taken into the calculation unit 32 as pulse signals synchronized with the rotation of the crankshaft or camshaft. Based on these pulse signals, the calculation unit 32 calculates the rotational speed (engine rotational speed) and rotational phase angle (crank angle) of the crankshaft.

  The ECU 31 detects the operating state of the internal combustion engine 10 based on detection signals from the accelerator sensor 41 and the rotation speed sensor 44. The ECU 31 controls, as switching means, at least one of the in-cylinder injection valve 21 and the port injection valve 22 so that the fuel injection mode of each of the injection valves 21 and 22 depends on the engine operating state. Switch.

  In the injection control device configured as described above, the injection for the port is exclusively performed during engine operation in a low water temperature region where the fuel spray is difficult to be vaporized (that is, when cold) or in a low rotation region where the piston speed is slow (particularly the idle region). Fuel injection by the valve 22 is performed. This is because if the fuel injection by the in-cylinder injection valve 21 is performed during engine operation in such a low water temperature region or a low rotation region, the spray form deteriorates or the combustion becomes slow, so that the port injection valve 22 This is because the combustion state tends to be deteriorated as compared with the case where fuel injection is performed.

  Incidentally, since the in-cylinder injection valve 21 is exposed to high-temperature combustion gas in the combustion chamber 11, deposits easily adhere to the injection hole portion of the injection valve 21. Such deposit can be blown off by fuel injection from the in-cylinder injection valve 21, but when the fuel injection is performed only by the port injection valve 22 as described above, the in-cylinder injection valve 21 Therefore, the temperature of the injection hole portion of the injection valve 21 rises, and deposits are further accumulated in the injection hole portion. This deposit hinders fuel injection from the nozzle hole, and causes a decrease in the fuel injection amount of the injection valve 21 when the in-cylinder injection valve 21 is used. If such a deposit reduces the fuel injection amount of the in-cylinder injection valve 21 and the injection amount becomes smaller than the appropriate value (required amount), there is a risk of causing misfire and consequently deterioration of the combustion state.

  For this reason, in the injection control apparatus according to the present embodiment, even in the operation region where the fuel injection by the port injection valve 22 is performed, the fuel injection only by the in-cylinder injection valve 21 is performed for a predetermined period under a predetermined condition. By forcibly switching the fuel injection mode to be performed, deposit accumulation in the nozzle hole portion is suppressed, and deposits already deposited are removed. In the present embodiment, forcibly switching the fuel injection mode specifically means switching the injection valve to be used to the in-cylinder injection valve 21.

The details of the fuel injection mode switching control for deposit countermeasures will be described below with reference to FIG.
In the present embodiment, a control routine corresponding to the first processing mode is prepared as a specific aspect of the fuel injection mode switching control executed by the ECU 31 (switching means). This control routine is stored in the storage unit 33 in the ECU 31.

  FIG. 2 is a flowchart showing a control routine according to the first processing mode. In the first processing mode, after the ignition switch IG is turned on, that is, after the engine is started, the injection valve is forcibly switched from the port injection valve 22 to the in-cylinder injection valve 21 for a predetermined period, thereby preventing deposits. It aims to plan. This control routine is executed through the ECU 31 as an angle interruption process for each predetermined crank angle, for example. Although illustration is omitted, when the ignition switch IG is turned on, the ECU 31 clears (→ "0") the mode control flag exinjdp as an initialization process for the control of the first process mode. Is supposed to run.

  As the interrupt process, when the process proceeds to this routine, the ECU 31 first determines whether or not the mode control flag exinjdp is “0” (step S110). At this time, when it is determined that the flag exinjdp is “1”, the ECU 31 ends this process.

  On the other hand, when determining that the flag exinjdp is “0” (step S110: YES), the ECU 31 detects the fuel injection amount QINJST (actual fuel injection amount) of the in-cylinder injection valve 21 at that time, It is determined whether or not the injection amount QINJST has reached a target value (target injection amount), in other words, whether or not the injection amount QINJST has decreased (step S120).

  In the determination process here, the ECU 31 serves as an injection amount detection means, for example, a fluctuation in the air-fuel ratio (A / F) learning value of the air-fuel mixture formed in the combustion chamber 11 (specifically, fuel injection in feedback control). The injection amount QINJST is detected by detecting the amount correction value).

  Here, when it is determined that the fuel injection amount QINJST has reached the target value (step S120: YES), that is, when it is determined that the injection amount QINJST has not decreased, the ECU 31 sets the mode control flag exinjdp. After the setting (→ “1”), the present process is terminated (step S130).

  On the other hand, when it is determined that the fuel injection amount QINJST has not reached the target value (step S120: NO), that is, when it is determined that the injection amount QINJST has decreased due to deposit, the ECU 31 forces the injection valve. Thus, the port injection valve 22 is switched to the in-cylinder injection valve 21, and the fuel injection by the in-cylinder injection valve 21 is performed for a predetermined period (step S140).

  At this time, in the present embodiment, the fuel injection mode is switched so that the fuel injection by the cylinder injection valve 21 is performed for each cylinder # 1 to # 4 by a predetermined cycle (for example, one cycle). Yes. As a result, deposits accumulated in the nozzle holes and further deposits such as carbon (non-solid materials such as deposits) which are the generation factors are blown off by the injection force, and the fuel injection of the in-cylinder injection valve 21 is performed. The amount QINJST can be restored to the target value. The ECU 31 once terminates the present process after performing such fuel injection by the in-cylinder injection valve 21.

  Thereafter, when the process again proceeds to this routine (first process mode) as the interrupt process, the ECU 31 determines whether or not the mode control flag exinjdp is “0” in step S110, and further, here, “0”. In step S120, it is determined whether the fuel injection amount QINJST is a target value. When the ECU 31 determines that the fuel injection amount QINJST is not the target value in the determination process in step S120, the ECU 31 forcibly switches to the in-cylinder injection valve 21 in the same manner as described above and uses the injection valve 21. Fuel injection is performed for a predetermined period.

  In this way, in the first processing mode, even when deposits are accumulated in the injection hole portion of the in-cylinder injection valve 21, the injection valve is forcibly switched to the in-cylinder injection valve 21, Deposits accumulated in the nozzle holes can be removed by blowing away with the injection force. Further, by performing fuel injection by such an in-cylinder injection valve 21, it is possible to take the heat of vaporization of the fuel from the nozzle hole portion and to cool the nozzle hole portion. As a result, deposits are also prevented from newly accumulating in the nozzle holes.

  Incidentally, when the engine is started immediately after the ignition switch IG is turned on, the temperature of the injection hole portion of the in-cylinder injection valve 21 and the temperature of the fuel injected from the injection valve 21 (fuel temperature) are higher than in the steady state. It has also been experimentally confirmed that the effect of blowing off the deposit is enhanced when the temperature of the nozzle hole and the fuel temperature are low (when cold). For this reason, in order to appropriately take measures against deposit, it is more preferable to use the time when the engine is started at a low temperature or fuel temperature of the nozzle hole.

As described above, according to the present embodiment, the following effects can be obtained.
(1) When the fuel injection amount QINJST (actual fuel injection amount) of the in-cylinder injection valve 21 is detected and the injection amount QINJST is less than the target value (target injection amount), the port injection valve is forcibly The in-cylinder injection valve 21 was switched from 22 to perform fuel injection by the in-cylinder injection valve 21 for each of the cylinders # 1 to # 4 for each predetermined cycle (one cycle in this example). As a result, the deposit or the like already accumulated in the injection hole portion of the in-cylinder injection valve 21 can be blown off by the injection force, and the injection amount QINJST can be recovered to the target value.

(2) Further, by depositing fuel by the in-cylinder injection valve 21 and cooling the nozzle hole portion accompanying the fuel injection, it is possible to suppress deposits from being newly deposited.
(3) In the present embodiment, on the condition that the fuel injection amount QINJST of the in-cylinder injection valve 21 is decreased, the forced injection is forced for each predetermined cycle only during the period until the injection amount QINJST recovers to the target value. Therefore, it was decided to switch to the same injection valve 21. The fuel injection by the in-cylinder injection valve 21 has a tendency that the air-fuel mixture is not sufficiently homogenized, but by performing the switching control only during the period until the injection amount QINJST recovers in this way, The influence of the deterioration of combustion resulting from the fuel injection by the cylinder injection valve 21 can be avoided as much as possible.

  (4) In the present embodiment, since it is possible to perform switching control to the in-cylinder injection valve 21 at the time of starting the engine having a high effect of blowing off deposits by fuel injection, it is possible to suitably take measures against deposits. .

In addition, you may implement this 1st Embodiment by changing into the following aspects.
In this embodiment, the fuel injection amount QINJST of the in-cylinder injection valve 21 is detected based on the fluctuation of the air-fuel ratio learning value, and when the injection amount QINJST is reduced, it recovers to the target value. The control for switching to the in-cylinder injection valve 21 is performed up to this point, but this may be performed under the following conditions. That is, since the deposit blowing effect is high when the temperature and fuel temperature of the nozzle hole are low as described above, based on the detection signal from the sensor that detects the temperature and fuel temperature of the nozzle hole, The above switching control may be performed under the condition that becomes below a predetermined temperature. In this way, it is possible to take a deposit countermeasure in a region where the blowing effect is high. The sensor that detects the nozzle hole temperature and the fuel temperature may be a sensor that can directly detect these temperatures, or the cooling water temperature may be detected using the water temperature sensor 42. A method of inferring based on the detection result may be used.

(Second Embodiment)
A second embodiment that embodies an internal combustion engine injection control apparatus according to the present invention will be described below with reference to FIGS. 3 and 4 with a focus on differences from the first embodiment.

  In the second embodiment, the specific mode of the fuel injection mode switching control executed by the ECU 31 (switching means) corresponds to the first processing mode described in the first embodiment. In addition to the control routine described above, a control routine corresponding to the second processing mode is prepared. These control routines are stored in the storage unit 33 in the ECU 31.

  FIG. 3 is a flowchart showing a control routine according to the second processing mode. In the second processing mode, the injection valve is forcibly changed from the ignition switch IG to the stop of the engine based on the mode control flag exinjdp according to the first processing mode. By switching from 22 to the in-cylinder injection valve 21, the purpose is to take measures against deposits. This control routine is executed through the ECU 31 as an angle interruption process for every predetermined crank angle, for example, triggered by the ignition switch IG being turned off.

  That is, when the process proceeds to this routine as an interrupt process triggered by the ignition switch IG being turned off, the ECU 31 first determines whether or not the mode control flag exinjdp is “1” (step S210). At this time, when it is determined that the flag exinjdp is “1” (step S210: YES), the ECU 31 ends this process. That is, when the mode control flag exinjdp is “1”, the ECU 31 is performing the deposit removal processing in the first processing mode, in other words, the fuel injection amount QINJST (actual fuel injection amount) is the target. It is determined that the value (target injection amount) has been recovered, and the present process is terminated to eliminate the need for deposit countermeasures in the second processing mode.

  On the other hand, when determining that the mode control flag exinjdp is “0” (step S210: NO), the ECU 31 forcibly switches the injection valve from the port injection valve 22 to the in-cylinder injection valve 21, Fuel injection by the cylinder injection valve 21 is performed for a predetermined period (step S220). That is, when the mode control flag exinjdp is “0”, the ECU 31 determines that there is a possibility of depositing and performs fuel injection by the in-cylinder injection valve 21.

  At this time, in the present embodiment, the fuel injection mode is switched so that the fuel injection by the in-cylinder injection valve 21 is performed for each of the cylinders # 1 to # 4. As a result, deposits accumulated in the nozzle holes and further deposits such as carbon (non-solid materials such as deposits), which are the generation factors, are blown off by the injection force, and the in-cylinder injection valve 21 The fuel injection amount QINJST can be recovered to the target value. After the fuel injection by the in-cylinder injection valve 21 is performed, the ECU 31 sets the mode control flag exinjdp (→ “1”) and ends the process (step S230).

  Thus, in the second processing mode, when the engine is stopped after the ignition switch IG is turned off, the injection valve is forcibly switched to the in-cylinder injection valve 21 so that the in-cylinder injection valve 21 Deposits accumulated in the nozzle hole can be removed. Further, by performing fuel injection by such an in-cylinder injection valve 21, it is possible to take the heat of vaporization of the fuel from the nozzle hole portion and to cool the nozzle hole portion. As a result, deposits are also prevented from newly accumulating in the nozzle holes.

  Incidentally, when such an engine is stopped, the influence of the deterioration of combustion due to the use of the in-cylinder injection valve 21 does not matter much. For this reason, it is preferable to use the time when the engine is stopped in order to prevent deposits.

  FIG. 4 shows the engine operation time and in-cylinder injection when the fuel injection mode switching control is executed in the second processing mode described in the present embodiment in addition to the first processing mode as a countermeasure against deposits. It is explanatory drawing which shows the relationship with the injection amount fall rate of the valve.

  As shown in the figure, the injection amount reduction rate of the in-cylinder injection valve 21 gradually increases as the engine operation time becomes longer, but now, after the ignition switch IG is turned off at time t1, When the second processing mode is executed and then the engine is forcibly switched to the in-cylinder injection valve 21, the injection amount reduction rate is recovered to some extent.

  Then, after the engine is started at time t2 (the ignition switch IG is turned on), the first processing mode as described above is executed, and the in-cylinder injection valve 21 is forcibly switched to the in-cylinder state. Deposits accumulated in the injection hole portion of the injection valve 21 are further removed, so that the injection amount reduction rate is almost recovered.

As described above, according to the present embodiment, in addition to the effects achieved in the first embodiment, the following effects are further achieved.
(1) After the ignition switch IG is turned off, the port injection valve 22 is forcibly switched to the in-cylinder injection valve 21, and fuel injection by the in-cylinder injection valve 21 is performed for each of the cylinders # 1 to # 4. The engine was stopped after every cycle. Thereby, deposits and the like accumulated in the injection hole portion of the in-cylinder injection valve 21 are blown off by the injection force, and the injection amount QINJST of the in-cylinder injection valve 21 can be recovered to the target amount.

  (2) Also, as in the first embodiment, fuel is injected by the in-cylinder injection valve 21 to cool the nozzle hole portion, thereby preventing deposits from being newly deposited when the engine is stopped. You can also

  (3) In the present embodiment, since the control of switching to the injection valve 21 is performed when the engine is stopped so that the influence of the deterioration of combustion caused by the fuel injection by the in-cylinder injection valve 21 does not become a problem, a countermeasure against deposits is made. Can be performed more suitably.

In addition, you may change and implement this 2nd Embodiment to the following aspects.
In the second embodiment, the processing related to the second processing mode is controlled in conjunction with the mode control flag exinjdp in the first processing mode described above. However, the control mode not linked to this flag exinjdp may be used. Good. That is, when the ignition switch IG is turned off, the switching control in the second processing mode is always executed regardless of the value of the flag exinjdp. In this way, it is possible to take measures against deposits by effectively using the engine stop when combustion deterioration is not a problem.

(Third embodiment)
Hereinafter, a third embodiment that embodies an internal combustion engine injection control apparatus according to the present invention will be described with reference to FIG. 5 with a focus on differences from the first and second embodiments.

  In the third embodiment, a control routine corresponding to the third processing mode is prepared as a specific aspect of the fuel injection mode switching control executed by the ECU 31 (switching means). This control routine is stored in the storage unit 33 in the ECU 31.

  FIG. 5 is a flowchart showing a control routine according to the third processing mode. In the third processing mode, during the operation in which the fuel injection by the port injection valve 22 is continuously performed, the deposit amount accumulated in the injection hole portion of the in-cylinder injection valve 21 is estimated, and the estimated value is obtained. Based on this, the purpose is to take measures against deposit by forcibly switching the injection valve from the port injection valve 22 to the cylinder injection valve 21 for a predetermined period. This control routine is executed through the ECU 31 as an angle interruption process for each predetermined crank angle, for example.

  Here, as a method for estimating the deposit amount, in the present embodiment, a method for estimating the deposit amount based on the operating state amount (engine operating state) of the internal combustion engine 10 having a correlation with the deposit amount. Is used.

  Specifically, the ECU 31 calculates an operation state quantity of the internal combustion engine 10 as estimation means, and estimates a deposit adhesion amount per time attached to the nozzle hole portion based on the calculated state quantity. Then, the ECU 31 accumulates the estimated deposit adhesion amount by an accumulation counter (not shown), and records the accumulated value as the deposit accumulation amount.

  Incidentally, as the operating state quantity used for estimating the deposit amount, the quantity correlated with the temperature of the nozzle hole and the engine combustion state, for example, the number of engine times detected by the rotational speed sensor 44, the accelerator sensor, etc. Parameters such as the engine load detected by the engine 41 and the rotation speed sensor 44, the cooling water temperature detected by the water temperature sensor 42, and the like can be used. In this estimation, in addition to a method of estimating these parameters individually, a method of estimating these parameters in combination, a method of weighting these parameters according to the degree of correlation with deposit accumulation, etc. Can be adopted.

In the third processing mode according to this control routine, switching control to the in-cylinder injection valve 21 is performed based on an estimated value obtained by estimating the deposit amount.
More specifically, when the process shifts to this routine as an interrupt process, the ECU 31 firstly deposits the amount estimated as described above, that is, the counter value ecinjdp of the integration counter exceeds a predetermined allowable value pl. It is determined whether or not there is (step S310).

  Here, when the counter value ecinjdp exceeds the allowable value pl, that is, when it is determined that the condition of ecinjdp> pl is satisfied (step S310: YES), the ECU 31 forces the injection valve to the port injection valve. The in-cylinder injection valve 21 is switched from 22 to perform fuel injection by the in-cylinder injection valve 21 (step S320).

  At this time, in the present embodiment, the fuel injection mode is switched so that the fuel injection by the in-cylinder injection valve 21 is performed for each of the cylinders # 1 to # 4 for each predetermined cycle (for example, for each cycle). . By starting the fuel injection by the in-cylinder injection valve 21, deposits accumulated in the injection hole portion, and further, deposits such as carbon (which is not a solid matter such as deposits) that are the generation factor thereof ) Is blown away by the injection force. Thereby, the fuel injection amount QINJST of the cylinder injection valve 21 can be recovered to the target value.

  After such fuel injection by the in-cylinder injection valve 21, the ECU 31 detects the fuel injection amount QINJST of the injection valve 21 and determines whether or not the injection amount QINJST has recovered to the target value ( Step S330).

  In the determination process here, as in the first process mode, the ECU 31 detects, for example, a change in the air-fuel ratio learning value of the air-fuel mixture formed in the combustion chamber 11 as the injection amount detection means. The injection amount QINJST is detected.

  Here, when it is determined that the fuel injection amount QINJST has recovered to the target value (step S330: YES), the ECU 31 clears the counter value ecinjdp of the integration counter (= “0”) and ends this processing. (Step S340). On the other hand, when determining that the fuel injection amount QINJST has not recovered to the target value (step S330: NO), the ECU 31 returns to step S320 and again performs fuel injection by the cylinder injection valve 21 for each cylinder #. One cycle is performed for each of 1 to # 4. Thereafter, similarly to the above, in step S330, the fuel injection amount QINJST is detected again, and it is determined whether or not the injection amount QINJST has recovered to the target value. By such a control loop in steps S320 and S330, the fuel injection amount QINJST is recovered to the target value.

  On the other hand, when determining that the counter value ecinjdp does not exceed the allowable value pl (step S310: NO), the ECU 31 again determines the counter value ecinjdp of the integration counter based on the operation state quantity of the internal combustion engine 10. Is calculated. Specifically, the accumulated amount eincinjdp is obtained by estimating the deposit amount newly deposited on the nozzle hole portion based on the operation state amount (step S350), and adding it to the current counter value ecinjdp. A new counter value ecinjdp is set (step S360). Thereafter, the ECU 31 once ends this process.

  When the process again enters this routine (third process mode) as an interrupt process, the ECU 31 determines in step S310 whether or not the counter value ecinjdp obtained in step S360 has exceeded the allowable value pl. to decide. If the ECU 31 determines in step S310 that the counter value ecinjdp exceeds the allowable value pl, the ECU 31 forcibly switches to the in-cylinder injection valve 21 in the same manner as described above. Fuel injection by the valve 21 is performed.

  As described above, in the third processing mode, when fuel injection by the port injection valve 22 is continuously performed, a value (counter value ecinjdp) in which the deposit amount is estimated exceeds the allowable value pl. The injection valve is forcibly switched from the port injection valve 22 to the in-cylinder injection valve 21 for a predetermined period. Thereby, the deposit accumulated in the injection hole portion of the in-cylinder injection valve 21 can be blown off by the injection force and removed. Further, by performing fuel injection by such an in-cylinder injection valve 21, it is possible to take the heat of vaporization of the fuel from the nozzle hole portion and to cool the nozzle hole portion. As a result, it is possible to suppress deposits from being newly deposited in the nozzle hole portion.

As described above, according to the present embodiment, in addition to the effects achieved in the first and second embodiments, the following effects are further achieved.
(1) In the present embodiment, the ECU 31 estimates the amount of deposit accumulated in the injection hole portion of the in-cylinder injection valve 21 during the operation in which the fuel injection by the port injection valve 22 is continuously performed. Is recorded as the counter value ecinjdp. When the counter value ecinjdp exceeds the allowable value pl, the port injection valve 22 is forcibly switched to the cylinder injection valve 21, and fuel injection by the cylinder injection valve 21 is performed for each cylinder # 1 to # 1. Each of # 4 was performed for each predetermined cycle (in this example, one cycle). As a result, deposits and the like accumulated in the injection hole portion of the in-cylinder injection valve 21 are blown off by the injection force, and the reduced injection amount QINJST can be recovered to the target value.

  (2) Also, as in the first and second embodiments, fuel is injected by the in-cylinder injection valve 21 to obtain a cooling effect accompanying the fuel injection, so that a new deposit is made when the engine is stopped. It is also possible to suppress deposition.

  (3) In the present embodiment, the deposit accumulation amount is estimated based on the operating state amount of the internal combustion engine 10, and switching control to the in-cylinder injection valve 21 is performed based on the estimated value (counter value ecinjdp). Therefore, it is possible to suitably take measures against deposits according to the engine operating state at that time.

  (4) In the present embodiment, during the operation by the port injection valve 22, during the period until the fuel injection amount QINJST of the in-cylinder injection valve 21 recovers to the target value, as in the first embodiment. For this reason, the switching control is forcibly switched to the injection valve 21 every predetermined cycle. Therefore, it is possible to avoid as much as possible the influence of deterioration of combustion caused by fuel injection by the in-cylinder injection valve 21.

<Other embodiments>
Each of the above embodiments may be implemented by changing to the following modes.
(A-1) In the first embodiment, on the condition that the fuel injection amount QINJST (actual fuel injection amount) of the in-cylinder injection valve 21 is less than the target value (target injection amount), It was set as the aspect which forcedly switches to the injection valve 21. FIG. This may be a mode in which forced switching is periodically performed in a predetermined period without depending on such conditions. In this case, as a specific mode at the time of “forcibly switching periodically with a predetermined period”, a mode in which switching is performed once every several minutes, a mode in which switching is performed once every several cycles, or the like can be employed. Even if it does in this way, the countermeasure against deposit can be suitably performed, avoiding the influence of the combustion deterioration by always using the cylinder injection valve 21 as much as possible.

  (A-2) In the third embodiment, the deposit amount of deposit deposited in the injection hole portion of the in-cylinder injection valve 21 is estimated, and the estimated deposit amount (counter value ecinjdp) is an allowable value pl. It was set as the aspect which forcedly switched to the injection valve 21 for cylinders on the condition that it is exceeding. This may be a mode in which the forced switching is periodically performed in a predetermined period, similarly to the above (a-1), without depending on such conditions.

  (A-3) In the first, second and third embodiments, when forcibly switching from the port injection valve 22 to the in-cylinder injection valve 21, it corresponds to each cylinder # 1 to # 4. The in-cylinder injection valve 21 to be controlled is switched at the same time. Valves that are switched sequentially while restricting the in-cylinder injection valves 21 to one or more of the in-cylinder injection valves 21 (here, four) without switching all of them simultaneously. It is good also as a switching mode which rotates. Even if it does in this way, the countermeasure against deposit can be suitably performed, avoiding the influence of the combustion deterioration by always using the cylinder injection valve 21 as much as possible. Further, in this way, each in-cylinder injection valve 21 is sequentially switched by a part of the valves (for example, one by one), so that the motor performance (torque) originally intended by using the port injection valve 22 is achieved. The deposit can be suitably removed and suppressed without lowering by switching to the in-cylinder injection valve 21.

  (A-4) Further, as in the above (a-1) and (a-2), when switching control is performed periodically (every few minutes or every several cycles) with a predetermined period, the above (a As in -3), some of the valves may be rotated and switched sequentially.

  In the first and third embodiments, when forced switching from the port injection valve 22 to the in-cylinder injection valve 21 is performed, fuel injection by the in-cylinder injection valve 21 is performed for each predetermined period. One cycle is performed for each cylinder # 1 to # 4. This may be performed for each of the cylinders # 1 to # 4 for two cycles, or for several more cycles so long as there is no concern about deterioration of combustion.

In addition, the mode in which the fuel injection by the in-cylinder injection valve 21 is performed for each predetermined period is not limited to the mode in which the fuel injection is performed for each predetermined cycle, and may be a mode in which the fuel injection is performed for a predetermined time.
The injection control device according to the present invention is provided with at least one of control routines corresponding to the first to third processing modes executed by the ECU 31 described in each embodiment. Any aspect is sufficient.

1 is a schematic configuration diagram showing an injection control device for an internal combustion engine according to the present invention. The flowchart which shows the control routine of the 1st process mode concerning 1st Embodiment. The flowchart which shows the control routine of the 2nd processing mode concerning 2nd Embodiment. Explanatory drawing which shows the correlation with engine operation time and the injection amount fall rate of the injection valve for cylinders. The flowchart which shows the control routine of the 3rd processing mode concerning 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Combustion chamber, 12 ... Intake passage, 12a ... Intake port, 21 ... In-cylinder injection valve, 22 ... Port injection valve (intake passage injection valve), 31 ... ECU (electronic control unit) , 41 ... Accelerator sensor, 42 ... Water temperature sensor, 43 ... Throttle sensor, 44 ... Revolution sensor, 45 ... Cylinder discrimination sensor, IG ... Ignition switch, pl ... Allowable value, QINJST ... Fuel injection amount (actual fuel injection amount), eincinjdp: integrated value.

Claims (8)

An in-cylinder injection valve that injects fuel into a cylinder of an internal combustion engine, an intake passage injection valve that injects fuel into an intake passage, and a switch that switches between fuel injection modes by drivingly controlling at least one of these injection valves An internal combustion engine injection control apparatus comprising:
The switching means executes control for forcibly switching the fuel injection mode so that fuel injection by only the in-cylinder injection valve is performed for a predetermined period in an operation region in which fuel injection by the intake passage injection valve is performed. An injection control device for an internal combustion engine characterized by the above. The switching means executes control for forcibly switching the fuel injection mode on condition that the temperature of the injection hole of the in-cylinder injection valve or the temperature of the fuel is detected to be equal to or lower than a predetermined temperature. The internal combustion engine injection control apparatus according to claim 1. The injection control device for an internal combustion engine according to claim 1 or 2, wherein the switching means executes control for forcibly switching the fuel injection mode until the internal combustion engine stops after the ignition switch is turned off. A detection means for detecting that the actual fuel injection amount of the in-cylinder injection valve is less than the target injection amount;
2. The switching means executes control for forcibly switching the fuel injection mode on the condition that the detection means detects that the actual fuel injection amount is less than the target injection amount. The injection control device for an internal combustion engine according to any one of claims 1 to 3. Further comprising estimation means for estimating the amount of deposit accumulated in the injection hole portion of the in-cylinder injection valve based on the engine operating state;
5. The control unit executes control for forcibly switching the fuel injection mode on condition that the deposit accumulation amount estimated by the estimation unit exceeds an allowable value. 6. An injection control device for an internal combustion engine according to claim 1. The injection control apparatus for an internal combustion engine according to claim 5, wherein the estimating means integrates the deposit amount per time estimated based on the engine operating state, and uses the accumulated value as the deposit amount. The injection control device for an internal combustion engine according to claim 1, wherein the switching means periodically executes control for forcibly switching the fuel injection mode with a predetermined period. The in-cylinder injection valve is provided corresponding to each cylinder of the internal combustion engine,
The internal combustion engine according to any one of claims 1 to 7, wherein the switching unit performs control to forcibly switch the fuel injection mode while sequentially rotating the control while limiting to some of the cylinders. Injection control device.

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